App‐based pelvic floor muscle training in pregnant and postnatal women: A prospective cohort study exploring factors associated with prevention and improvement of urinary incontinence

Abstract Background and Aims Pelvic floor muscle training (PFMT) is recommended for continent pregnant women and postnatal women experiencing urinary incontinence (UI). The app Tät® has been developed for the treatment of stress UI with a focus on PFMT. The aim of this study was to investigate factors associated with the improvement of incontinence symptoms and retained continence in pregnant and postnatal women who used the app. Methods A prospective cohort study was carried out based on user questionnaires from the app Tät®. We included pregnant and postnatal women who answered the inclusion questionnaire between June 19, 2019 and September 19, 2020. The questionnaire included questions about the frequency and amount of leakage, the impact that UI has on everyday life, and experienced improvements at follow‐up. We analyzed factors associated with improvement and retained continence using logistic regression. Results We included 10,307 pregnant and 13,670 postnatal women, and 44% of the pregnant women and 52% of the postnatal women were incontinent. A total of 3680 women were included in the follow‐up analysis, and 52% of the pregnant incontinent women and 73% of the postnatal incontinent women experienced improvement. Pregnant women who performed PFMT and used the app at least once per week had increased odds of improvement (odds ratio [OR]: 1.83, 95% confidence interval [CI]: 1.01–3.29 and OR: 3.38, 95% CI: 1.94–5.90, respectively) compared to those who performed no training and had no app usage. Postnatal women who used the app at least once per week and had more severe incontinence had increased odds of improvement (OR: 4.26, 95% CI: 2.37–7.64 and OR: 1.11, 95% CI: 1.05–1.16, respectively). Conclusions The app Tät® is widely used by pregnant and postnatal women in Sweden for the prevention and treatment of UI. Majority of the women with incontinence experienced improvement after using the app. Regular PFMT and app use seemed to be important factors for experiencing improvement.


| INTRODUCTION
Urinary incontinence (UI), defined as involuntary leakage of urine, 1 is common and affects 25%-45% of all women. 2 Stress urinary incontinence (SUI) is leakage during physical exercise, coughing, or sneezing, and is the most frequent subtype. 1 Pregnancy and childbirth are risk factors for developing UI, especially SUI. 2 During pregnancy, the prevalence of SUI ranges from 18.6% to 60% and it increases during late pregnancy. 3 During the 3 months after childbirth, the prevalence of UI is around 30%, 4 and the frequency of postpartum SUI is higher in women who have a vaginal delivery than those who have a cesarean Section. 5 The present-day recommendations are that pelvic floor muscle training (PFMT) should be offered to all continent pregnant women and postnatal women experiencing UI. 6 However, there is insufficient evidence that PFMT is effective for treating UI during pregnancy and postpartum and there is a need for further investigation into PFMT in these specific groups. 7,8 UI can have a significant impact on quality of life. 9 Despite this, only 31% of those who suffer seek professional help, and one reason could be the feeling of embarrassment when talking to a physician about it. 10,11 PFMT is the first-line treatment for all types of UI, 2 and a mobile app is an easily available and cost-effective way to offer PFMT. 12 Via an app, women who are not willing to ask for face-toface care can receive the instructions through a smartphone. The app Tät ® has been developed for the self-treatment of SUI, with a focus on PFMT. Its effects have been evaluated in a randomized-controlled trial (RCT), which showed significant improvements in terms of clinical symptoms, number of leakages, and quality of life, compared to a control group. 13 Pregnant women were not included in the RCT.
Since 2015, the app has been free to download from App Store and Google Play and we follow its use in the real world. 14 The aim of this study was to investigate the use of the freely available app Tät ® during pregnancy and the postnatal period.
Specifically, the aim was to investigate factors associated with the improvement of incontinence symptoms in pregnant and postnatal women who used the app Tät ® . It also investigated factors associated with retained continence in pregnant women who used the app.

| MATERIALS AND METHODS
This was a prospective cohort study based on data from the mobile app Tät ® . Inclusion criteria were as follows: users who answered the inclusion questionnaire between June 19, 2019 and September 19, 2020; stated that they were female; were 18-50 years old; and were either pregnant or had given birth no more than 3 months before downloading the app (i.e., were postnatal). Follow-up questionnaires completed within 90-135 days after inclusion were included since we only wanted answers from active users (Figure 1).  15 The responses make up a total score of between 0 and 21, which can be divided into different severity categories: 1-5 (slight), 6-12 (moderate), 13-18 (severe), and 19-21 (very severe). 16 We defined users who answered that they had both some amount of leakage and some frequency of leakage as incontinent.
The ICIQ-UI SF also includes a self-diagnostic question about the situations in which leakage occurs. Users who answered that they had leakage when they coughed, sneezed, or were physically active but had no leakage before they reached the toilet were defined as having stress UI. Users who answered that they had leakage before they reached the toilet but not when they coughed, sneezed, or were physically active were defined as having urgency UI. Users who answered that they had both symptoms of stress UI and urgency UI were defined as having mixed UI.
After 3 months, a follow-up questionnaire appeared with questions about pregnancy, childbirth during the last 3 months, use of the app, frequency of performed PFMT, and incontinence symptoms based on the ICIQ-UI SF. The question about PFMT frequency had five response options: never, less than once a week, 1-6 times per week, daily, three times daily, or more. The question about app use also had five response options: not at all, about once a month, about once a week, about once a day, and several times a day. There was also a question about the subjective change in symptoms based on the validated patient's global impression of improvement (PGI-I), which has seven response options ranging from "very much worse" to "very much better." 17 We defined incontinent users who answered that their condition was "a little better," "much better," and "very much better" on the PGI-I as showing "improvement." Answering the questionnaires was optional and the app could be fully used even if the users declined to participate in the study. The users were informed that their responses were sent anonymously and encrypted to the research database. The users gave their informed consent by ticking a box in the questionnaires. A unique app identification linked the user's response at inclusion to the same user's response at follow-up, but the answers could not be traced back to a specific person. No information about the user's name, social security number, email address, IP address, or phone number was ever collected.

| Statistical analyses
Descriptive statistics were presented as frequencies with percentages and mean values with standard deviations. Differences between groups were analyzed using the χ 2 test for categorical variables and analysis of variance (ANOVA) for continuous variables. Changes in mean ICIQ-UI SF scores were analyzed using a paired samples t-test, and differences in mean change between groups were analyzed using ANOVA.
Potential confounders were included in the analysis of association: age, education level, stage of pregnancy, mode of delivery, childbirth during the last 3 months, number of childbirths, ICIQ-UI SF score at inclusion, type of incontinence, PFMT frequency, and app usage frequency. If a variable like PFMT and app use frequency had too few answers in one response category to perform analysis, that response category collapsed with the closest category. All variables were first analyzed in separate logistic regression models, and the associations with "improvement" or "retained continence" were estimated. Variables that had a p < 0.2 were included in the multiple logistic regression models. Odds ratios (OR) and 95% confidence intervals (CIs) were estimated. Age and ICIQ-UI SF scores were analyzed as continuous variables, whereas the other variables were analyzed as categorical variables. p < 0.05 were considered statically significant in all analyses. All data were analyzed using SPSS ® version 27 and there were no missing values in the analyses.

| RESULTS
A total of 53,205 app users answered the inclusion questionnaire. Of these 23,977 met the inclusion criteria for baseline analysis, of which 10,307 (43%) were pregnant and 13,670 (57%) were postnatal ( Figure 1).
In pregnant women, the mean age was 31 years. The majority lived in Sweden (n = 8962) and had a university education (n = 7625).
Two-thirds (n = 6878) had not experienced childbirth when downloading the app, and most women (n = 8385) had downloaded it for preventive purposes. The proportion of incontinent women was higher in Weeks 27+ of pregnancy than in Weeks 0-13 of pregnancy (51.1% vs. 33.8%). Around two-thirds (n = 3131) of the incontinent women had SUI (Table 1).
In postnatal women, the mean age was 32 years and the majority had only had a vaginal delivery (n = 11,846). Most women lived in Sweden (n = 12,371) and had university education (n = 9499). The proportion of incontinent women was higher in those who had only had a vaginal delivery compared to those who had only had a cesarean section (53.1% vs. 33.4%). Almost half of the incontinent women had SUI (n = 3524) ( Table 2).
A total of 3680 women were included in the follow-up analysis.
More than two-thirds of all women had used the app (72.9%) and performed PFMT (69.5%) at least once per week during the last month. A higher proportion of women who were in Weeks 14-26 and Weeks 27+ of pregnancy than those in Weeks 0-13 of pregnancy had used the app and performed PFMT daily (23.6% and 29.2% vs. 16.2%). In postnatal women, the frequency of PFMT training and app usage was similar regardless of the mode of delivery (Tables 3 and 4).
The ICIQ UI-SF scores at inclusion were higher in postnatal women than in pregnant women. Women who were in Weeks 0-13 of pregnancy at inclusion had no improvement in the ICIQ-UI SF score after 3 months. Women who were in Weeks 27+ of pregnancy improved more than women who were in Weeks 14-26 of pregnancy (1.90 vs. 0.49 points). The postnatal women improved on average by 2.61 points, and there was no significant difference between women who had had different modes of delivery (p = 0.734) ( Table 5).
Of the 826 pregnant women that were incontinent at inclusion, 432 (52.3%) had improved at follow-up ( Figure 2). In the analyses of potential factors associated with "improvement," age, education level, stage of pregnancy, number of childbirths, mode of delivery, frequency of PFMT, and frequency of app users had a p < 0.2 (data not shown) and were thus included in the multiple regression model. In the multiple regression model, PFMT frequency and app usage frequency were significantly associated with "improvement" (Table 6).
Of the 982 postnatal women with incontinence at inclusion, 716 (72.9%) had improved at follow-up ( Figure 2). In the analyses of potential factors associated with "improvement," the ICIQ-UI SF score at inclusion, mode of delivery, type of incontinence, frequency of PFMT, and frequency of app users had a p < 0.2 (data not shown) and were thus included in the multiple regression model. In the multiple regression model, the ICIQ-UI SF score, mode of delivery, and app usage frequency were significantly associated with "improvement" (Table 6).
Of the 1071 pregnant women that were continent at inclusion, 773 (72.2%) were still continent at follow-up. In the analyses of potential factors associated with "retained continence," age, PFMT frequency, and given birth at follow-up had a p < 0.2 and were thus included in the multiple regression model (data not shown). Only age had a significant association with "retained continence" (OR: 0.95, 95% CI: 0.92-0.99, p = 0.007).

| DISCUSSION
We found that 52% of the pregnant incontinent women and 73% of the postnatal incontinent women experienced improvement after 3 months of using the app Tät ® . At least weekly PFMT and use of the app increased the odds of experiencing improvement in pregnant women. Higher symptom severity and at least weekly app usage increased the odds of experiencing improvement in postnatal women, whereas having had a cesarean section decreased the odds of experiencing improvement. Further, we found that 72% of the continent's pregnant women retained continence after 3 months of using the app, with an older age decreasing the odds of staying continent during pregnancy.
The strengths of this study include its prospective study design and a large number of participants included, which was possible due to the short, anonymous questionnaire. A further strength is the medical relevance of app-based treatment, which can reach many women, including those not wanting to ask for face-to-face care.
Also, the fact that we used the validated ICIQ-UI SF and PGI-I increases the reliability and enables comparison to other studies.
Additionally, since the study was performed in the same clinical setting as the app is meant to be used, it increases the transferability to app users outside of the study.
The main limitation of the study is the lack of a control group, which means we cannot know whether the improvements are due to PFMT, other concomitant treatment, or a natural improvement occurring over time. The same applies to whether the continent pregnant women would have stayed continent regardless of whether they used the app or not. However, since PFMT and app usage were associated with improvement, we assume they contributed to the results. Moreover, we cannot know if only women that experienced an improvement continued to use the app. Furthermore, the women in this study were highly educated with 71% having a university education compared to 58.5% of all women aged 25-44 in Sweden in 2019. 18 It is thus possible that these women are not comparable to all pregnant and postnatal women in need of treatment for UI. We nonetheless found no association between education level and T A B L E 1 Baseline characteristics of pregnant women who answered the inclusion questionnaire participants, together with the experience of an earlier study on the real-world use of the app. 14 One explanation for the low follow-up rate could be that women who were continent and had downloaded the app for prevention of UI were lacking the motivation for continuing using the app. An earlier study found that incontinent users had a higher response rate than continent users, indicating that they were more likely to stick with the program. 14 Another explanation could be that continent women and those with less difficult symptoms only downloaded the app for information and never intended to continue using it for 3 months. It is also possible T A B L E 5 Change in ICIQ-UI SF scores in pregnant and postnatal women with incontinence at inclusion who also answered the follow-up questionnaire, according to groups assigned at inclusion  that only users that experienced an improvement continued using the app which thereby could have influenced the results.
Postnatal women had both a higher level of severity of incontinence and larger improvements than pregnant women. An earlier study found that more severe incontinence led to a greater ICIQ-UI SF score reduction, 14 so it is, therefore, possible that a higher symptom severity increases the possibility of improvement. However, these findings might also indicate that PFMT is not as beneficial for pregnant women as for postnatal women, which can be deemed to agree with a study by Woldringh et al. 20 which found that PFMT was not effective during pregnancy for women who were already affected by UI.
Only pregnant women who were in mid or late pregnancy at inclusion had an improved ICIQ-UI SF score. It has previously been suggested that the result of PFMT is highly dependent on the degree and duration of the training. 21 It is thus possible that women in early pregnancy did not improve due to a lower frequency of PFMT and app usage.
All postnatal women had an improved ICIQ-UI SF score. It has previously been suggested that a change of 2.5 points in the ICIQ-UI SF score is clinically relevant at group level, 22 and therefore our results of 2.61 points' improvement among postnatal women are clinically significant. We, therefore, believe that the incontinence symptoms of all postnatal women, independent of the mode of delivery, could improve via app-based PFMT.
The association between improvement and a higher frequency of PFMT and app use has also been found by others, which strengthens the suggestion that treatment adherence is important for improvement. 21,23 T A B L E 6 Factors associated with "improvement" among pregnant and postnatal women with incontinence at inclusion who also answered the follow-up questionnaire For example, Nyström et al. 24 found that at least weekly PFMT and use of the app increased the odds of improvement among nonpregnant/ nonpostnatal women. Furthermore, they found a correlation between the frequency of PFMT and the frequency of app use, suggesting that the effects of these factors might overlap. However, the app also includes information and lifestyle advice, which could explain the beneficial effects of only using the app.
The finding that a higher ICIQ-UI SF score at inclusion would increase the odds of improvement is in contrast to what earlier studies have found. [24][25][26][27][28] However, these studies used different outcome measurements. For example, Lindh et al. 23 found that a higher ICIQ-UI SF score predicted a reduction of ≥3 points, whereas a lower ICIQ-UI SF score predicted higher treatment satisfaction.

| CONCLUSION
A mobile app focused on PFMT is widely used by pregnant and postnatal women in Sweden both for preventing and treating UI.

CONFLICT OF INTEREST
The logos Tät and Tät.nu are registered as trademarks by The Swedish Patent and Registration office for eContinence AB, a Swedish e-health company founded in July 2021, with the aim to maintain, spread, commercialize, and further develop the apps created within the research project Tät.nu (eContinence.se). Ina Asklund is a co-founder and shareholder of eContinence AB. eContinence AB had no involvement in study design; collection, analysis, and interpretation of data; writing of the report; or the decision to submit the report for publication.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request. Erika Löjdahl had full access to all of the data in this study and takes complete responsibility for the integrity of the data and the accuracy of the data analysis.

ETHICS STATEMENT
The study was approved by the Regional Ethical Review Board, Umeå

TRANSPARENCY STATEMENT
Ina Asklund affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.